1. Field of Invention
The present invention is directed to monitoring of water quality and, more particularly, to a water-monitoring apparatus with an anchor.
2. Related Prior Art
While developing, the world is encountering a more and more serious problem of pollution. Water pollution could be the worst among all sorts of pollution. A lot of pollutants are dumped to reservoirs and open channels from fixed sources, e.g., factories and farms, or from mobile sources, e.g., vehicles. Such pollutants may be released into water, or may be dumped on the land and then washed into the water by rain. Once introduced into the water, such pollutants inevitably increase costs in treating the water and very often harm human bodies, life stock and aquatic lives.
Therefore, it is important to solve these problems of pollution. However, before any proper measure can be taken to solve the problem of water pollution, pollutants and extent of pollution must be determined. Hence, various quality parameters of the water must be monitored.
In early days, prior to analyses, water was manually sampled. Manual sampling has always been expensive and cumbersome. Therefore, manual sampling was conducted on an irregular basis and rarely.
To achieve regular and frequent sampling, it must be done automatically. There have been installed some conventional monitoring stations into which water is automatically pumped through pipes. It is, however, found difficult to have the pipes catch up with the water level changing vigorously from season to season. When the water level becomes too low for the pipes to reach, it is impossible to pump water through the pipes.
To make sure that the water can be monitored continuously, there have been devised some water-monitoring apparatuses in which sensors are carried by means of a buoy tied to a bank or a well by means of a cable. To have the buoy float on the water when the water level is low, a sufficiently long cable is used. However, the cable allows the buoy to drift for a long distance in any direction when the water level is high. As the buoy drifts, the cable often tangles with miscellaneous objects, e.g., twigs. This could seriously affect the operation of the sensors.
To prevent the cable from. tangling with miscellaneous objects, there has been devised a length control device in which the cable is wound on a reel operatively connected with a motor. The motor can be activated to rotate the reel to adjust a length of the cable extending from the reel so that the sensors can always be immerged in water. However, the motor consumes a lot of energy.
In addition, to transmit signals from the sensors to a monitoring station, the cable is connected to the monitoring station through a signal relay including a mandrel electrically connected with the cable. The mandrel rotates together with the reel. The signal relay further includes a brush electrically connected with the monitoring station. The brush does not rotate. The mandrel is in rotational engagement with the brush, thus allowing the mandrel to rotate with respect to the brush while allowing the signals to be transmitted from the mandrel to the brush. However, friction between the mandrel and the brush interferes with the rotation of the reel and wears out the brush after serving for a period of time.
However, none of the above-mentioned water-monitoring apparatuses is suitable for use far from the bank. Hence, a water-monitoring apparatus has been devised to include a sensor carried by means of a buoy connected via a cable with an anchor or weight for holding on to a reservoir bottom or an ocean bed. Obviously, such a water-monitoring apparatus with an anchor can be employed far from the bank since it does not have to be tied to the bank. To have the buoy float on the water when the water level is high, a sufficiently long cable is used. However, when the water level is low, the cable allows the buoy to drift for a long distance in any direction. Sometimes, the buoy may drift to and get grounded on a slope by the water. This could seriously affect the operation of the sensor.
Therefore, the present invention is intended to alleviate or even obviate the afore-mentioned drawbacks that are encountered in the prior art.
It is an objective of the present invention to provide a water-monitoring apparatus for use far from the land.
It is another objective of the present invention to provide a water-monitoring apparatus capable of automatically tracing water level.
It is another objective of the present invention to provide a water-monitoring apparatus with a sensor-carrying cable of an automatically adjustable length.
It is another objective of the present invention to provide a water-monitoring apparatus with a sensor-carrying cable wound on a reel capable of automatic rotation for adjusting a length of the sensor-carrying cable extending from the reel.
In accordance with an aspect of the present invention, a water-monitoring apparatus includes at least one sensor carried by a buoy. The sensor is used to detect a water quality parameter. A reel is mounted on the buoy. A coil spring is used to exert a substantially constant torque on the reel. A cable is wound on the reel. The cable includes an upper end tied to the reel and a lower end tied to an anchor or weight for holding on to a water bottom.